SU924645A1 - Device for dynamic hysteresis loop registration - Google Patents

Description

(5) DEVICE FOR REGISTRATION OF DYNAMIC HYSTERESIS HINGES

one

The invention relates to magnetic measurements and is intended to register hysteresis cycles in a dynamic re-magnetization mode.

A device for recording dynamic hysteresis loops is known, containing a test sample with a magnetizing winding connected to a source of magnetizing current and a strobe pulse shaping unit connected to the mixer inputs, and a recording device. The device is equipped with a mutual inductance coil and two integrator adders, one of which is connected between the measuring winding and the second input of one of the mixers, and the second between the mutual inductance coil and the second input of the second mixer, and the outputs of both mixers are connected to the registrar of the SP.

However, this device has a low detection accuracy of hysteresis cycles with a high coefficient of rectangularity.

Closest to the proposed device is a device for recording magnetization curves of ferromagnetic materials in a dynamic mode, containing a source of undercurrent connected to a fast-changing sawtooth driver and a magnetizing winding, in series with which a reference resistor is connected, as well as two stroboscopic mixers, of which is connected to the integrator, the input of which is connected to the measuring winding, the second to the reference resistor, outputs, stroboscopic mixes Ithel connected to the recording device, and their control inputs to the gating pulse shaper which is connected via a comparison unit formirovagel E bystroizmen kitsegos and medlennoizmen yuschegos voltage t21.

In the known device, strobe pulses are formed, the phase shift of which relative to the phase of the recorded process changes with a constant speed. For hysteresis loops with a greater degree of rectangularity, in some areas a sharp change in induction occurs with a slight change in the field intensity, therefore the number of reading points and, consequently, the registration accuracy in this area are small.

The purpose of the invention is the measurement accuracy.

The goal is achieved in that a device for recording dynamic hysteresis loops containing a source of magnetizing current, one output of which is connected to a reference resistor through a magnetizing winding, and the other output connected to serially connected fast-changing voltage driver, comparator unit and strobe pulse former , the output of which is connected with the inputs of the first and second mixers, the second input of the first mixer through the integrator connected to the measuring winding, W The second input of the mixer is connected to the midpoint between the reference resistor and the magnetizing winding, the outputs of the first and second mixers are connected to the first and second inputs of the recorder, respectively, and the second input of the comparator is connected to the output of the slow voltage generator, the second connected second measuring winding is additionally introduced and a diode bridge, the output of which is connected to the second input of the fast-changing driver, for example.

FIG. 1 shows a functional diagram of an apparatus for registering dynamic hysteresis loops; in fig. 2 - stress diagrams for his work.

The device contains a slow-voltage driver 1, a comparison unit 2, a fast-voltage driver 3, a gate pulse driver, a diode bridge 5, a current source 6, sample 7, measuring windings 8 and 9, a magnetizing winding 10, a reference resistor 11, integrator 12, mixers 13 and 14, recorder 15; The fast variable voltage driver 3 consists of a series of 16 square pulse drivers in series, trigger 17 and integrator I8j, the slow voltage driver 1 and 3 fast voltage voltage connectors are connected to a comparison unit 2, which is connected to gate 4 4 5 pulses , control mixers 13 and H, a source 6 of current is connected to the input of the former 16 rectangular pulses, and 0 measuring winding 8 is connected to one of the inputs of the integrator 18 through a diode bridge 5- Magnetizing winding 10 is connected to current source 6, reference resistor 11 and mixer 1A. Measuring winding 9 through 5 integrator 12 is connected to mixer 13- The outputs of the mixers are connected to recorder 15.

The device works as follows.

0 An alternating current flows from the current source 6 through the low-winding winding 10 and the reference -sistor-11 resistor. This ensures the remagnetization of the sample 7. The voltage from the reference resistor 11 d is proportional to the magnetic field strength in the sample, and from the measuring winding 9 - the voltage proportional to the rate of change of induction, which g is integrated by the integrator 12, from the output of which the voltage proportional to the induction is removed. These two voltages are fed to the mixers 13 and 1, to the control inputs of which a signal is sent from the strobe pulse generator C, which transforms the spectrum into the low frequency range. The mixers 13 and I receive the voltage from the recorder 15. The recording speed of the hysteresis cycles and the number of read points depend on the rate of change of the phase shift between the strobe pulses and the magnetizing current.

Claims (2)

 Strobe pulses are formed as follows. The alternating voltage from the current source 6 is supplied to the shaper 16 square pulses, where rectangular pulses are formed, which are converted by the trigger 1 into pulses whose frequency is twice less. These pulses arrive at one of the inputs of the integrator 18. In this case, you will see ramp-shaped pulses on the course of the fast-changing voltage driver 3 (figure 2, curve 19). However, when remagnetizing a ferromagnetic sample with a high degree of rectangular hysteresis loop, the induction in the sample drastically changes its value and the EMF on the measuring winding 8 has the form of short-duration impulses that are converted into unipolar diode bridge 5 (Fig. 20.) to the second input of the integrator 18, in the result of which the voltage at the output of the shaper 3 rapidly changing to the yarn has the shape of a curve 20 (Fig. 25). The pulses on the measuring winding 8 occur at the time of a sharp change in induction and, when applied to the integrator 1B, result in a change in the shape of the output voltage, so that at the moment of a sharp change in the induction the rate of change of the output voltage of the fast-changing voltage shaper 3 increases which corresponds to the change in the slope of the curve 20 (FIG. 2B). If the voltage-varying voltage from the voltage-changing generator 1 is slow, and the voltage-changing voltage from the speed-varying voltage generator 3 is equal (Fig. 25, the intersection point of curves 20 and 21), unit 2 of the comparison and the C strobe driver -pulses form strobe pulses, the phase shift of which relative to the magnetizing current smoothly changes. The rate of change of the phase shift between strobe pulses depends on the ratio between the slope of the curves; slow-changing voltage and quick-change voltage. For known devices, the rapidly varying voltage has a sawtooth shape, and the rate of change of voltage is constant. . In the proposed device, the rate of change of the rapidly changing kS6 voltage on the areas of abrupt change of induction is greater (Fig. 2d), therefore the rate of change of the phase shift of the strobe pulses on this part, the less, and the number of strobe pulses (reading points) increases, which leads to increase the accuracy of registration of hysteresis loops in these areas. Thus, the introduction of the measuring winding 8, connected via a diode bridge 5 to the fast-changing voltage driver 3, reduces the rate of change of the phase shift of the strobe-impunces in areas with a sharp change in induction, which leads to an increase in reading points in these areas and an increase in the accuracy of recording loops hysteresis with a high rectangle ratio. Claims An apparatus for registering dynamic hysteresis loops containing a source of magnetizing current, one output of which is connected through a magnetizing winding with a reference resistor, and the other output connected to serially connected fast-varying voltage driver, comparator unit and strobe pulse former, the output of which is connected to the inputs of the first and second mixers, the second input of the first mixer through the integrator connected to the measuring winding, the second input of the second mix It is connected to the midpoint between the reference resistor and the magnetizing winding, the outputs of the first and second mixers are connected respectively to the first and second inputs of the recorder, and the second input of the comparator is connected to the output of the slow voltage generator, characterized in that, in order to improve the measurement accuracy The second measuring winding and a diode bridge, the output of which is connected to the second input of the quick-change voltage generator, are additionally introduced into it. Sources of information taken into account during the examination 1. USSR author's certificate N 555356, cl. G 01 R 33/12, 1976. 2. Factory Laboratory, 1962, No. 3, p. 27. Us J f fl f f J 11